| Submerged arc furnace is a necessary production equipment in the ferroalloy industry.The power frequency AC power supply is used for operation.Not only is the power consumption serious,the power factor is low,but the three-phase is difficult to balance,the efficiency is low,and the production cost is high.The use of DC power supply can not only reduce the busbar inductive voltage drop,but also increase the power factor to achieve the purpose of energy saving and high efficiency.Therefore,the current large-capacity submerged arc furnace power supply is developing in the direction of DC.This paper studies the DC submerged arc power supply system with a rated capacity of 33000 k VA.The system consists of three 12-pulse DC power supplies with a rated output of 100 k A / 175 V,which can be equivalent to 36-pulse rectifier on the high-voltage AC side of the transformer.Due to the high current output characteristics of the power supply,each main circuit chooses a rectifier transformer and then a thyristor rectification scheme.The rectifier circuit is a 12-pulse three-phase bridge in-phase anti-parallel circuit topology.This scheme is expanding the output current.At the same time,the power factor of the system is improved;through the reasonable design of the main circuit and the rectifier arm structure and the use of strong triggering and other measures,the current sharing effect of the parallel devices is improved.The experimental results show that the current sharing coefficient is significantly improved compared with the currently used strip rectifier arm structure;Adopts DSP as the core of the digital control unit for power control,monitoring and protection functions.Finally,the software and hardware are debugged and simulated to verify the reliability of the design scheme.The results show that the main circuit and control circuit designed in this paper can meet the technical requirements,the current sharing coefficient is above 0.8,and its operating effect and performance are great. |
PDF Full Text Request